Chapter 5: Tropical Rainforests

Canopy Layer

• 20 - 30 m high

• Crowns interlock to form a big mass of branches & leaves.

• Blocks 97 - 98% of sunlight

Emergent Layer

• trees 30m or higher

• only tallest & strongest trees

• very sunny

Undergrowth Layer

• beneath canopy layer

• sparse vegetation

• little sunlight

Characteristics of Rainforests

• most plants evergreen bc lots of sunlight & rainfall

• DON’T shed leaves seasonally

• plants continuously regrow leaves to replace old ones

• contains more plant species than any other ecosystem type

• no one plant species shows up significantly more than others

Broad Leaves

has large surface area to absorb more sunlight hence make more food

Waxy Leaves

reduce water vapour lost through transpiration due to high temp.

Drip tips

allow rainwater to flow off easily so leaves dry fast. (otherwise, got fungi + bacteria grow)

Buttress Roots

• up to 5m above ground. rest of roots don’t go very deep

• provides support so trees stays upright & doesn’t topple

• dead leaves decompose in topmost layer of soil, so nutrients concentrate there. shallow underground roots absorb that.